1. Field of the Invention
The present invention relates to surgical devices for providing access into a body cavity of a patient during a surgical procedure, and more particularly, to a pneumatically sealed trocar assembly.
2. Description of the Related Art
Laparoscopic, or “minimally invasive” surgical techniques are increasingly more common in hospitals today. Benefits of such procedures include reduced trauma to the patient, reduced opportunity for infection, and decreased recovery time. Such procedures within the abdominal cavity are typically performed through a device known as a trocar or cannula, which facilitates the introduction of laparoscopic instruments into the abdominal cavity of a patient.
Additionally, such procedures commonly involve filling or “insufflating” the abdominal (peritoneal) cavity with a pressurized fluid, such as carbon dioxide, to create what is referred to as a pneumoperitoneum. The insufflation can be carried out by a trocar equipped to deliver insufflation fluid, or by a separate insufflation device, such as an insufflation needle. Introduction of surgical instruments into the pneumoperitoneum without a substantial loss of insufflation gas is desirable, in order to maintain the pneumoperitoneum.
During typical laparoscopic procedures, a surgeon makes three to four small incisions, usually no larger than about twelve millimeters each, which are typically made with the trocar devices themselves, typically using a separate inserter or obturator placed therein. Following insertion, the inserter is removed, and the trocar allows access for instruments to be inserted into the abdominal cavity. Typical trocars often provide means to insufflate the abdominal cavity, so that the surgeon has an open interior space in which to work.
The trocar must provide a means to maintain the pressure within the cavity by sealing between the trocar and the surgical instrument being used, while still allowing at least a minimum freedom of movement of the surgical instruments. Such instruments can include, for example, scissors, grasping instruments, occluding instruments, cauterizing units, cameras, light sources and other surgical instruments. Sealing elements or mechanisms are typically provided on trocars to prevent the escape of insufflation gas. Sealing elements or mechanisms typically include a duckbill-type valve made of a relatively pliable material, to seal around an outer surface of surgical instruments passing through the trocar. However, sealing in this manner is not usually complete, such seals cannot seal between multiple instruments, and such seals also inhibit free movement of the surgical instruments and/or removal of tissue through the trocar. Such seals are also vulnerable to damage during the surgical procedure. Alternatively, a flapper valve or spring-loaded trap door can be used. However, these types of mechanical valves suffer from similar drawbacks.
Most valves, and particularly duckbill-type valves, which include resilient valve members that directly contact surgical instruments, not only interfere with the movement of surgical instruments, but reduce the ability of a surgeon to accurately sense the patient anatomy on which the surgeon is operating. Minimally invasive surgical procedures are carried out with a visualization aid such as a camera, and as a result, depth perception on the part of the surgeon is inhibited. Accordingly, the ability to physically sense resistance of structures and of tissues through movement of the surgical instruments plays an important role in a successful and safe surgical procedure. Frictional forces imparted on surgical instruments by contact of the aforementioned mechanical valves can mask the sensory signals, i.e., the haptic perception, that the surgeon might otherwise use to determine precisely what is occurring at the opposite end of the surgical instruments being used. Accordingly, improvements to sealing technologies that allow unencumbered access while maintaining a pneumoperitoneum, are desired.